German Patent 2,839,496 C2 discloses a method of transferring conveyed goods from a driven roller conveyor that is movable along a rail, whereby the conveying direction is perpendicular to its moving direction, to a storage location embodied as a conveyor drivable through frictional contact. The rail-mounted, driven roller conveyor is moved in a direction parallel to its conveying direction until frictional contact is established with the drivable roller conveyor forming the storage location.
An apparatus for carrying out the method disclosed in German Patent 2,839,496 C2 includes a driven roller conveyor mounted on a rail carriage, a friction roller drive train, a drive mechanism for the driven roller conveyor, and a drivable roller conveyor forming the storage location. The apparatus further includes another drive mechanism arranged between the driven roller conveyor and the rail carriage, which may, for example, be a spindle drive or a chain drive. The driven roller conveyor is supported on guides, such as guide rollers or rail members, extending perpendicularly to the movement direction. The additional drive mechanism pushes the driven roller conveyor forward until the friction wheel comes into contact, at a predeterminable contact pressure, with a frictional tread surface of the drivable roller conveyor.
In the above described known method and apparatus, it is necessary that both the loading arrangement, as well as the storage arrangement are provided with rollers. It is clear that the cost and effort involved in equipping such a storage facility with rollers forming the compartment floor of each individual storage compartment is quite high, and becomes prohibitive for manufacturing a multi-storied warehouse including a multi-storied storage rack having such a construction. Furthermore, the maintenance cost and effort are also very high for such an arrangement. Furthermore, with such an arrangement it is necessary to attach an additional lift or hoist to the multi-storied facility, and additionally provide a roller conveyor of the above described type in each warehouse aisle for loading or inserting goods into the individual storage compartments of the storage racks. Moreover, it is only possible to relocate or restack goods from one storage location to another storage location within the multi-storied storage facility through a series of temporary, intermediate placements of the goods. European Patent Application 0,133,472 discloses a high-rise multi-storied storage facility in which an incoming piece of freight, for example a freight container, is first delivered by an auxiliary apparatus, namely a lift or hoist. Then, the freight is delivered to a particular storage level, where it is transferred to or taken over by a further auxiliary vehicle. The auxiliary vehicle then carries the freight in the individual aisles of the storage rack to a position in front of the appropriate storage location, and then deposits the freight at the storage location by means of a raising and lowering movement. With such an arrangement, it is only possible to carry out a simple storing and unstoring or removing of containers.
German Patent Laying Open Document 3,207,860 A1 discloses a conveyor device for a multi-storied warehouse, in which a lift or hoist lifts large containers up to the individual floors of the warehouse. At each individual floor, the containers are further handled by an additional conveying device. The conveying device includes additional raisable and lowerable conveyor carriages, each including its own drive means. Each conveyor carriage receives either one large container or two smaller containers and then drives through an alley to bring the containers to the appropriate compartment of a storage rack. An auxiliary wagon moves the container or containers into the compartment. The wagon is lowered to deposit the container(s) and is then retracted onto the carriage that drives in the alley. Thereupon, a new storage cycle can be initiated, whether it is to place a container into a storage compartment or to remove a container from a storage compartment. It is possible to relocate individual containers only by the repeated, temporary placement of the containers at intermediate storage locations, until the containers are finally deposited at the desired storage location, for example where a new batch load of several containers is being assembled.
The use of additional lift or hoist means necessarily involves an additional conveying step during the storing or unstoring procedure. Thereby, the storing or unstoring cycle necessarily requires a longer time to be completed. Furthermore, if containers are to be relocated or restacked within one floor or storage level of the warehouse, the lift is blocked during the time period necessary for the relocation. In other words, additional containers to arrive at or depart from this storage level cannot be transported. When containers are to be relocated from one storage level to another, the lift is also occupied or blocked from receiving or releasing other containers, because the lift is needed as an auxiliary device for carrying out the relocation.
The same concerns or disadvantages described above apply when transporting and storing large pallets or large individual work pieces, which themselves have a sufficient strength to be conveyed into the intended storage location in a multi-storied storage rack without being placed into a container or other supporting arrangement.
Furthermore, the above described methods and apparatus cannot be used to select, in advance, a desired arbitrary storage location for goods that are to be stored either semi-permanently at a final location or temporarily at an intermediate location.